My son's complaint about the tubes that I buy, that should work based on these numbers, is that when he inflates the tube, then it pokes out from underneath the tire. So what size should we buy, and any suggestions of where to find it? Looking online, it looks like 700c is often equated with 27".
And tied into this question is, he hasn't ever used a liner, but he has frequent flats. I'm thinking of getting a couple of liners, but do you have to adjust the tube size when you use a liner?

Bob I think he means liner as in tube puncture protection, rim tape is used to cover nipples and holes under the tube. He wants to know about the liners used between the tube and tire. If the tube is popping out of the tire then there is a bead seat issue, this can be caused by many things.as far as tube liners I do not use them but others here ( Nigel) would be happy to tell you about them

There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"

Thank you everyone, and especially Nigel,
That is very helpful information.
We will try what you recommend, and I will have my son research the proper way to install a tube so that it seats correctly.
~Diane

Also note that an incorrectly installed inner tube will have a pinch flat really fast. So do take some time to do it correctly. I first install one side of the tyre, then put a bit of air into the tube, just so it is round-ish. Then I put the valve into the valve hole and push the tube into the tyre, working away from the valve on both sides - otherwise I tend to move the tube inside the tyre and the valve will no longer poke out radially from the rim and there would be quite some stress on the valve / tube interface.
Then, starting at the valve again, I push the second side of the tyre into the rim. Starting at the valve is sometimes really necessary when you have narrow rims, plus it makes it easier to get the tube seated correctly inside the tyre (see comment on the valve above...), again, work away from the valve in both directions. Sometimes I need a tyre lever to force the last bit of the tyre onto the rim, but that is bad style and prone to errors, it is so easy to pinch the tube, and then you have to start it all over again... yes, I know that from experience - I was under time pressure - and no, after I broke the tube when mounting the tyre I did not make it in time.
Then, inflate tyre a bit and push the tyre on the rim to both sides, kneading it a bit, all the way around, so that it seats properly. Then, inflate to final pressure.
I ride without liners, but I use tyres that are a bit puncture resistant. I had... three or four flats in the last years. One because the valve was leaking, the others were with nasty road debris, 1cm long glass or metal pieces. One was because I rode with a worn tyre on my beater and the tube was bulging out of a hole... oops. I have latex inner tubes on my road bike that are a bit more puncture resistant than the light butyl (normal) tubes. What I want to say is that there are some flats that cannot be avoided using liners. The ones with the road debris could, the others not so much.

What kind of flats does he get? Does he run the correct tyre pressure? Are they on the inside or the outside of the tube? Is the rim tape still ok, or is it cracked at some place? Are they always in one spot? Search the tube very carefully for thorns or glass when you have a flat. If the cause is not removed, the next tube will be flat soon.

Thy tyres Nigel recommended look like a good deal, very suitable for road and dirt roads / forest "roads" (at least in my part of the world).

Nigel, When I looked at the tube you recommended, it says 700c, but also 27" (not 28", which is what we need). Will it really fit?
Our tires also say 42-622.
Also, to clarify, my son says the tube pokes out from under the tire, and then he lets air out, and it goes back into place. He thinks I just haven't bought the right size. (which is why I am really trying to find the exactly right size to buy!) Also, I had him read the detailed info re proper technique, and he will check the rim for possible rough spots, etc.
Thanks again

(08-27-2013, 03:33 PM)Diane Wrote: Nigel, When I looked at the tube you recommended, it says 700c, but also 27" (not 28", which is what we need). Will it really fit?
Our tires also say 42-622.
Also, to clarify, my son says the tube pokes out from under the tire, and then he lets air out, and it goes back into place. He thinks I just haven't bought the right size. (which is why I am really trying to find the exactly right size to buy!) Also, I had him read the detailed info re proper technique, and he will check the rim for possible rough spots, etc.
Thanks again

It will fit.

The tube size has nothing to do with: "..the tube pokes out from under the tire,...". The tire is not seated properly on the rim, which can be caused by method, a problem with the rim, a problem with the tire, or a combination.

With no tube at all, the tire should sit fairly snug on the rim, and require a bit of effort to remove once installed with no tube. If the tire comes off easily with no tube, there is a problem that needs to be addressed first.

Sizing can be confusing. The new 29" bikes have xx-622 tyres that would theoretically fit on your rim, which is referred to as 28". Look athttp://sheldonbrown.com/tire-sizing.html
there is a list with all common and some arcane sizes, split by use.
What kind of bike does your son have? Are there any markings on the rim of the wheels? There should be a sticker on it with size information.

(08-28-2013, 01:59 AM)Joe_W Wrote: Sizing can be confusing. The new 29" bikes have xx-622 tyres that would theoretically fit on your rim, which is referred to as 28". Look athttp://sheldonbrown.com/tire-sizing.html
there is a list with all common and some arcane sizes, split by use.
What kind of bike does your son have? Are there any markings on the rim of the wheels? There should be a sticker on it with size information.

Thank you Joe. the sheldonbrown site is certainly interesting, and detailed!
The rim says:
Safety Line
Alu 6061-T6
Weinmann
700CX28C/38C
ETRTO 622X19

This is a very tall/large bike, btw. Purchased for my tall husband.
I ordered the tubes Nigel recommended, and will post after they arrive, and we see how they fit.
~Diane

700C and 622 is "regular" 28 inch wheels by today's standard, used on racing and touring bikes (and others). Tyre sizes are confusing on several points; there are lots of old bikes still in daily use, and there are numerous rim sizes which still is common in Holland and UK, but hardly ever seen in US (happens now and then though). This is one way it makes the situation complicated. 42-622 is luckily a standard size (ETRTO) wich cannot be confused (I almost dare bet on it) and available from all makers and all kinds of different styles. In real life tires vary quite a bit from maker to maker too, especially Asian brands can seem a bit off mark some times (Shin-Shen f.ex.). Tires should in theory be made to millimeter accuracy with the ETRTO standard but they are some times not. Most confusing is the sizing in inches, 26" is very often not 26", and neither is 28" !